The First Three Seconds: a Review of Possible Expansion Histories of the Early Universe

By R. Allahverdi, M. Amin, A. Berlin, N. Bernal, C. Byrnes, M. Sten Delos, A. Erickcek, Miguel Escudero, Daniel G. Figueroa, K. Freese and 16 more. The Open Journal of Astrophysics, 2020

282 citations recorded by the source corpus.

It is commonly assumed that the energy density of the Universe was dominated by radiation between reheating after inflation and the onset of matter domination 54,000 years later. While the abundance of light elements indicates that the Universe was radiation dominated during Big Bang Nucleosynthesis (BBN), there is scant evidence that the Universe was radiation dominated prior to BBN. It is therefore possible that the cosmological history was more complicated, with deviations from the standard radiation domination during the earliest epochs. Indeed, several interesting proposals regarding various topics such as the generation of dark matter, matter-antimatter asymmetry, gravitational waves, primordial black holes, or microhalos during a nonstandard expansion phase have been recently made. In this paper, we review various possible causes and consequences of deviations from radiation domination in the early Universe - taking place either before or after BBN - and the constraints on them, as they have been discussed in the literature during the recent years.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/3cae5080288af03ae231546dc27c7e0109d223c6

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In Astronomy and Astrophysics

1. Marek Lewicki
2. John Ellis
3. V. Vaskonen
4. G. White
5. Kanu Sinha
6. Daniel Vagie
7. Huai-Ke Guo
8. J. No

In Nuclear and High Energy Physics

1. Marek Lewicki
2. John Ellis
3. G. White
4. Kanu Sinha
5. V. Vaskonen
6. B. Carr
7. Florian Kuhnel

Citations in the corpus

• Phase transitions in an expanding universe: stochastic gravitational waves in standard and non-standard histories (2020, background): “J C A P 0 1 ( 2 0 2 1 ) 0 0 1 This is important, since growing evidence suggests that the standard assumption of radiation domination prior to Big Bang Nucleosynthesis may be too naive [56, 57].”
• Updated predictions for gravitational waves produced in a strongly supercooled phase transition (2020, background): “) ˇ100 for simplicity. Whether the eld uctuations decay quickly into radiation or not, the total energy during the transition is the same, and the initial abundance of GWs is not modied signicantly [61]. However, after production the GWs redshift in the same way as radiation, and a period of matter ”